Electrical terminal and method of applying same to electrical conductors



March 29, 1966 ELLlOTT 3,243,763

ELECTRICAL TERMINAL AND METHOD OF APPLYING SAME T0 ELECTRICAL CONDUCTORS Filed Jan. 1.3, 1964 .Fzfln 071 Moward [Ilia it United States Patent ELECTRICAL TERMINAL AND METHOD OF AP- PLYIN G SAME T0 ELECTRICAL CONDUCTORS Howard A. Elliott, Detroit, Mich., assignor to Essex Wire Corporation, Fort Wayne, Ind., a corporation of Michigan Filed Jan. 13, 1964, Ser. No. 337,292 7 Claims. (Cl. 339-223) This invention relates to electrical terminals or connectors and to methods for applying them to non-metallic conductors, and it particularly relates to means for terminating cables with non-metallic conducting cores, wherein the terminals withstand very high pulling forces before the terminals become separated from the table.

Today, it is common practice to utilize non-metallic conductors, as glass core cables, for various applications, particularly in the automotive field. Generally, such conductors comprise a plurality of fine strands or threads of various non-metallic materials, such as, cotton, linen, rayon, glass, or combinations thereof. Non-metallic cables are conventionally used as ignition cables in automotive engines. One of the problems encountered in using non-metallic core :cables is that the electrical terminal mounted on the end of a cable is often pulled from its associated cable when it is desired to remove the cable from an associated electrical component, as a spark plug. Furthermore, a good electrical connection between a nonmetallic conductor and a terminal is difficult to provide, as sparking often occurs between the terminal and the conductor.

Therefore, it is a primary object of this invention to provide electrical termination means for non-metallic core cables and a method for accomplishing such temination, wherein problems encountered with prior art terminations are substantially avoided.

It is also an object of this invention to provide an electrical termination wherein a high pull 'force is required before a terminal becomes separated from its associated cable.

It is a further object of this invention to provide an electrical termination of a high pull strength, wherein a metallic mass is crimped to the projecting end of a nonmetallic core and a hardened head of plastic is positioned at the outer end of the .core, prior to the mounting of the terminal to the cable, whereby co-operation between the metallic mass and the plastic bead provides high pull strength for the termination.

It is another object of this invention to provide an improved means and method for terminating a stranded, non-metallic conductor having insulation therearound in order to provide a termination having both an increased pull strength and an improved electrical connection between the non-metallic core and the terminal.

Further purposes and objects of this invention will appear as the specification proceeds.

A particular embodiment of the present invention is illustrated in the accompanying drawings wherein:

FIGURE 1 is a plan view of a cable having a nonmetallic core, with insulation stripped from one end of the cable;

FIGURE 2 is a view similar to FIGURE 1, except that a plastic bead is shown at the outer end of the nonmetallic core;

FIGURE 3 is a view similar to FIGURE 2, except that a metallic mass or terminal is crimped on the core, intermediate the end of the insulation and the plastic bead;

FIGURE 4 is a view taken along the line 44 of FIGURE 3;

FIGURE 5 is an enlarged plan view of my termination,

3,243,763 Patented Mar. 29, 1966 showing the metallic mass, the plastic bead, and an electrical terminal mounted on the insulation and the metallic mass;

FIGURE 6 is a view taken along the line 6-6 of FIGURE 5;

FIGURE 7 is a sectional view taken along the line 77 of FIGURE 5;

FIGURE 8 is a sectional view taken along the line 88 of FIGURE 6; and

FIGURE 9 is asectional view, similar to FIGURE 8, except that an elbow type electrical terminal is shown mounted on the cable.

Referring to the drawings, my improved termination for a cable having a non-metallic core is illustrated most clearly in FIGURES 5, 8, and 9. The cable 10 has a nonmetallic conducting core 12, which is comprised of a plurality of fine threads, fibers or strands; a solid core may also be utilized. The core 12 is covered by a suitable thickness of insulation 14, which is stripped, according to conventional practice, at one end, whereby the non-metallic core 22 projects outwardly therefrom. The tip or outer end 16 of the core 12 is provided with a head 18 of hardened plastic; the bead 18 is adapted to hold the strands of the core 12 together in order to provide a substantially unitary bundle of strands. Advantageously, the head 18 is made of a plastic material such as nylon, Bakelite, epoxy resin, rosin, etc. Preferably, nylon is utilized since it provides improved terminations at relatively high temperatures, in the range of about 200-325 F.

Intermediate the head 18 and the end of the insulation 14, there is mounted a metallic mass 20, preferably formed of lead, which may be secured to the stranded non-metallic core 12 by suitable means, as crimping. Referring to FIGURES 4 and 7, the mass 20 initially has a generally U-shaped form. The legs 22 of the terminal 20 are passed around the outwardly projecting portion of the core 12, intermediate the end of the insulation 14 and the head 18, and are then forced together.

An electrical connector or terminal 24 is mounted on the insulation 14 at one end thereof and also on the lead mass 20, to thus provide a proper electrical connection between the terminal 24 and the core 12. Desirably, the terminal 24 has a stepped barrel portion 26 whereby the rear portion of the barrel 26 is firmly mounted on the cable insulation 14 and the adjacent stepped portion of increased diameter is firmly positioned on the mass 20, to thus provide a good connection between the core 12 and the terminal 24.

The terminal 24, together with the lead mass 20 and nylon head 18, provide a good electrical connection and a termination of high pull strength. When it is desired to remove the cable 10 from an electrical component, as a spark plug (not shown), as the cable 10 is pulled, the lead mass 20 co-acts with the nylon bead 18 upon abutment therebetween to maintain the terminal 24 in firm connection with the core 12, to thus avoid the separation of the terminal 24 from the cable 10 at normal pulling forces and at normal internal combustion engine operating temperatures. Other types of terminals, as elbow terminals 28, shown in FIGURE 9 may also be utilized with my improved electrical termination.

In my process for terminating a glass core ignition cable 10, the cable insulation 14 is first stripped or removed from one end of the cable 10 in a conventional manner in order to provide an outwardly projecting core 12, as shown in FIGURE 1. After stripping the insulation 14, a liquid plastic is applied to the outer end or tip 16 of the core 12 and is allowed to harden thereon, to thus provide the plastic head 18. Although various plastics may be used, nylon is preferably used since it provides a termination of extremely high pull strength, even at elevated engine temperatures; it has been found that a termination using a nylon bead 18 will withstand a 140 pound pull at a temperature of about 325 F. It is also desirable that the plastic does not flow'along the strands of the core 12 and thereby interfere with the electrical connection between the core 12 and the terminal 24.

After the head 18 has hardened on the end of the core 20, a lead terminal 20 is interposed on the core 12, intermediate the end of the insulation 14 and the bead 18. The legs 22 of the terminal 20 are passed around the core 12 and are crimped together, without causing any appreciable longitudinalextrusion of the lead mass 20. Desirably, the opposite ends of the terminal 20 are spaced slightly from both the nylon bead 18 and the end of the cable insulation. Harder metallic materials, such as brass, may be utilized but a termination using such a material is weaker than those utilizing lead or other soft materials. Lead has the further advantage of tightly gripping the glass strands of the core 12 without breaking them.

After a lead terminal 20 is crimped in place, an electrical terminal 24, as a spark plug terminal, is crimped about the lead terminal 20 and about the end of the cable insulation 14. Upon crimping the spark plug terminal 24 to the lead terminal 20, the lead terminal is 7 caused to be extruded, reducing the outer diameter thereof; as the lead expands longitudinally, it may become positioned at one end against the cable insulation 14 and at the other end against the nylon head 18, and, in some case, may partially flow over the bead 18. As previously set forth, the barrel 26 of the spark plug terminal 24 has a stepped portion with a reduced diameter adapted to grip the cable insulation 14, whereby a stop or abutment is provided between the lead mass 20 and the terminal 24, to further assist in increasing the pull strength of the termination. Thus, there is co-operation between, the terminal 24, the lead mass 29, the bead 18, to provide an improved electrical termination of increased pull strength. Furthermore, good electrical contact is provided between the core 12 and the terminal 24, sparking therebetween being substantially eliminated.

While in the foregoing there has been provided a detailed description of a particular embodiment of the present invention, it is to be understood that all equivalents obvious to those having skill in the art are to be included within the scope of the invention as claimed.

"What I claim and desire to secure by Letters Patent 1. An improved electrical termination comprising a non-metallic conductor having insulation therearound, said conductor projecting beyond said insulation, a head of plastic at the outer end of the projecting portion of said conductor, a metallic mass positioned on said conductor intermediate said bead and the end of said insulation, and

an electrical terminal mounted on both said insulation and said metallic mass.

2. The termination of claim 1 wherein said bead is made of epoxy resin and said metallic mass is made of a material selected from the group consisting of brass and lead.

3. An improved electrical termination comprising a stranded non-metallic conductor having insulation there around, said conductor projecting beyond the end of said insulation, a nylon bead at the end of the projecting portion of said conductor, a lead mass positioned around said conductor intermediate the end of said insulation and said head, and an electrical terminal crimped on both said lead terminal and said insulation.

4. The termination of claim 3 wherein said electrical terminal includes a stepped barrel portion which is adapted to provide a stop for said lead mass.

5. An improved method for terminating a non-metallic conductor having insulation therearound, said method comprising the steps of applying a plastic head to the end of said conductor, mounting a metallic mass on said conductor intermediate the end of said insulation and said bead, and securing an electrical terminal to both said insulation and said metallic mass.

6. An improved method for terminating at stranded non-metallic conductor having insulation therearound, said method comprising the steps of applying a plastic bead made of epoxy resin to the end of said conductor, mounting a metallic mass made of a material selected from the group consisting of lead and bass on said conductor intermediate said bead and the end of said insulation, and securing an electrical terminal to both said insulation and said mass.

7. An improved method for terminating a stranded glass core conductor having insulation therearound, said method comprising the steps of stripping the insulation from one end of said conductor, applying a nylon bead to the end of said conductor, crimping a lead mass on said conductor intermediate said bead and the end of said insulation, and crimping an electrical terminal to both the lead terminal and the adjacent cable insulation.

References Cited by the Examiner UNITED STATES PATENTS 1,575,656 3/1926 Stratford et al. 339-276 2,449,373 9/1948 Falge et al. 339223 3,079,674 3/1963 Shortt 29155.55 X

FOREIGN PATENTS 344,987 3/1931 Great Britain. 634,358 3/1950 Great Britain.

5 JOSEPH D. SEERS, Primary Examiner.

P. A. CLIFFORD, Assistant Examiner. 

1. AN IMPROVED ELECTRICALLY TERMINATION COMPRISING A NON-METALLIC CONDUCTOR HAVING INSULATION THEREAROUND, SAID CONDUCTOR PROJECTION BEYOND SAID INSULATION, A BEAD OF PLASTIC AT THE OUTER END OF THE PROJECTING PORTION OF SAID CONDUCTOR, A METALLIC MASS POSITIONED ON SAID CONDUCTOR INTERMEDIATE SAID BEAD AND THE END OF SAID INSULATION, AND AND SAID METALLIC MASS. 